Isoelectric Focusing has proven to be a useful tool in the evaluation of allergenic extracts. This type of electrophoresis serves as a basis for examining the immunological activity of the extract, and identifies the IgE binding components in the products. Differences in the behavior of IgE binding in the sera of allergic individuals may be surveyed, and sera may be selected for testing pools with these methods, thereby assuring a fair representation of IgE binding activity in quantitative tests. Preparative IEF, using a new apparatus , has permitted the isolation of single components from allergenic extracts, separating non-IgE binding and IgE binding components in sufficient quantities for analysis and further testing. The development of a 2D electrophoresis method using IEF as the first dimension has been initiated this year. This method has the potential to assist in the isolation and sequencing of IgE binding extract components.